The reaction of chiral sulfinimines 1c-g derived from aliphatic aldehydes with TMSCN in the presence of CsF gave α-amino nitriles in high diastereoselectivity and yield. Α,β-Diamino acid derivatives were also obtained in high diastereoselectivity from the reaction of 2-aziridinesulfinimines 1h and 1i followed by ring-opening of the products with thiophenol. The presence of hydrogen at the α-position of the C=N double bond is crucial in this TMSCN addition reaction.